Engineering of functional contractile cardiac tissues cultured in a perfusion system.

Overcoming the limitations of diffusional transport in conventional culture systems remains an open issue for successfully generating thick, compact and functional cardiac tissues. Previously, it was shown that perfusion systems enhance the yield and uniformity of cell seeding and cell survival in thick cardiac constructs. The aim of our study was to form highly functional cardiac constructs starting from spatially uniform, high density cell seeded constructs. Disk-shaped elastomeric poly(glycerol sebacate) scaffolds were seeded with neonatal rat cardiomyocytes and cultured for eight days with direct perfusion of culture medium or statically in a six-well plate. In the perfusion experimental group, the integrity of some disks was well maintained, whereas in others a central hole was formed, resulting in ring-shaped constructs. This allowed us to also study the effects of construct geometry and of interstitial flow versus channel perfusion. The ring-shaped constructs appeared to have a denser and more uniform deposition of extracellular matrix. In response to electrical stimulation, the fractional area change of the ring-shaped constructs was 7.3 and 2.7 times higher than for disk-shaped tissues cultured in perfusion or statically, respectively. These findings suggest that a combination of many factors, including scaffold elasticity and geometry and the type of perfusion system applied, need to be considered in order to engineer a cardiac construct with high contractile activity.